With the development of semiconductor package technology, various package types are developed for semiconductor devices, wherein a semiconductor chip is firstly mounted on a package substrate or a conductive wire frame, the semiconductor chip is electrically connected to the package substrate of the conductive wire frame, and then an encapsulant is employed to encapsulate. Ball grid array (BGA) is an advanced semiconductor package technology, whose feature is to employ a package substrate to mount the semiconductor chip, wherein self-alignment technology is employed to mount a plurality of solder balls to the back surface of the package substrate, so as to accommodate more I/O connections on a semiconductor chip carrier board having a same area for meeting the requirement of high integration of the semiconductor chip. The solder balls are used to solder and electrically connect the whole package unit to external devices.
However, current BGA structure can not meet the electrical and heat spreading requirements under the circumstances of more pins (1500 pin) and high frequency (5 GHz). FCBGA structure can be used in products having said more pins and high frequency, however, whose package cost is high, and there are many limitations in this technology, especially in the electrically connecting portion thereof, for the sake of environment protection, electrically connecting materials, such as Pb, one of the solder materials, are forbidden to be used, electrical, mechanical qualities are unstable while using other replacement materials.
For this reason, a new method of a semiconductor chip is embedded in a semiconductor chip carrier board is proposed. As shown in FIG. 1, U.S. Pat. No. 6,709,898 discloses a semiconductor package having heat spreading function. As shown in the figure, the semiconductor package comprises a heat spreader 102, the heat spreader 102 comprises at least one recess 104; a semiconductor chip 114, a non-active surface 114B of the semiconductor chip 114 is mounted in the recess 104 via a thermally conductive adhesive material 118; a circuit build-up structure 122 formed on the heat spreader 102 and the semiconductor chip 114 via circuit build-up technology.
Referring to FIG. 2, a section view showing the spreader mounted in the semiconductor package. As shown in the figure, the recess 104 is extended to a certain depth from the upper surface of the heat spreader 102 to the inner thereof; the semiconductor chip 114 is mounted on the bottom surface of the recess 104 via the thermally conductive adhesive material 118; when the adhesive material is filled in the recess 104, it can not be fully filled in the space of the recess 104 because of the surface tension of the adhesive material per se, which may easily form voids 130. In the following fabricating procedure of the semiconductor package, when the semiconductor package having voids 130 is placed in the high temperature environment, the air in the voids 130 is expanded because of the heat, therefore resulting popcorn problem which degrades the reliability and quality of products.